The head of the police's counterterrorism and transnational crime unit, Monirul Islam, said Mr Karim faced no charges in connection with the attack.

"None of those arrested alive named Hasnat Karim. His involvement was not found during any stage of the investigation. That's why we have not included his name in the charge sheet," Mr Islam was quoted as saying by news site bdnews24.com.

Mr Karim's wife told BBC Bengali on Tuesday that he had yet to be released.

The attack was claimed by the Islamic State group, although Bangladesh disputed this and said a local militant group was responsible.

Five militants inside the cafe were killed by police. Eight others have now been charged over their involvement, six of whom are in custody, according to Mr Islam.